TECHNICAL FIELD
[0001] The present invention relates to a cephalopod feeder, to a feeding method using the
same, and to cephalopods reared by the feeding method.
BACKGROUND ART
[0002] In recent years, since consumers have strong preferences and interests in resource
conservation, there is a demand for the development of aquaculture techniques for
cephalopods.
[0003] For example, Patent Document 1 discloses an octopus raising shelter and an octopus
aquaculture system. Non-Patent Document 1 discloses observations on octopus raising.
[0004] On the other hand, in the aquaculture of cephalopods, although better feeding methods
are becoming important, knowledge of cephalopod feeding methods has been insufficient.
CITATION LIST
Patent Literature
Non-patent Literature
SUMMARY OF THE INVENTION
Technical Problem
[0007] As described above, for cephalopods, sufficient knowledge has not been obtained as
to what feeding method should be used to better feed them and what kind of feeding
method is better suited for improving the flesh quality of cultured cephalopods while
maintaining an appropriate raising environment in aquaculture with the purpose of
producing a source of food and other things.
[0008] In order to solve the above-described problems, the present invention is intended
to provide a cephalopod feeder capable of better raising cephalopods, a feeding method
using the same, and a cephalopod reared by the feeding method.
Solution to the Problem
[0009] The present invention is described below.
- [1] A cephalopod feeder including an outer shell having a concave portion and a feed
placed in the concave portion.
- [2] The feeder according to [1], in which the outer shell is shaped to be held by
an arm of a cephalopod.
- [3] The feeder according to [1] or [2], in which the outer shell has a strength capable
of withstanding pressure from an arm of a cephalopod.
- [4] The feeder according to any one of [1] to [3], in which the feed is an adherent
feed.
- [5] A method of feeding a cephalopod using the feeder according to any one of [1]
to [4].
- [6] A cephalopod reared by the feeding method according to [5].
ADVANTAGEOUS EFFECTS OF THE INVENTION
[0010] The present invention can provide a feeder, a feeding method for cephalopods that
can provide better feeding of them, prevent deterioration of the rearing environment,
and better rear the cephalopods, and a cephalopod with improved flesh quality through
such good rearing.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] FIGS. 1A to 1G are schematic diagrams illustrating feeders.
DESCRIPTION OF EMBODIMENTS
[0012] In the present specification, the term "step" includes not only an independent step
but also a step that cannot be clearly distinguished from other steps, provided that
an intended object of such a step is achieved.
[0013] In the present specification, numerical ranges indicated by "to" are ranges including
the numerical values appearing before and after "to" as the minimum value and maximum
value, respectively.
[0014] In the present specification, in a case where a plurality of substances corresponding
to each component are present in the mixture, an amount of each component in the mixture
means a total amount of the plurality of substances present in the mixture, unless
otherwise specified.
[0015] In the present specification, the terms "not greater than" and "less than" in regard
to percentages mean ranges including 0%, which is the case of "not contained", or
a value undetectable by present means, unless a lower limit is specifically stated.
[0016] Feeders and feeding methods according to embodiments of the present invention will
be described below.
[0017] A feeder (cephalopod feeding device) according to an embodiment of the present invention
is used for raising cephalopods. The feeder may be installed in a tank for raising
cephalopods, or outside the tank for raising cephalopods as long as the cephalopods
can reach it with their arms and be fed.
[0018] The "arms" of cephalopods described in the present embodiment refer to protrusions
that grow from the heads of cephalopods. Eight-armed cephalopods including octopus
have eight arms, and ten-armed cephalopods including squid have ten arms. Of the ten
arms possessed by the ten-armed cephalopods, the two long ones are called tentacles
and may be used for eating a feed.
[0019] Cephalopods may be raised in a manner appropriate for the type of cephalopods. The
raising of cephalopods may be performed in a land tank or in a marine cage. Raising
in a land tank makes it easier to observe the feed intake. For raising cephalopods,
a plurality of individuals may be raised together in a tank or a cage, or each one
may be raised in an individual tank or a cage.
[0020] In the above-described raising environment, as to the installation of the feeder
according to the present aspect, the device may be installed at the time of each feeding,
or it may be installed permanently and the feed placed in the feeder replaced appropriately.
[0021] In addition, as to an embodiment of installation of the feeder, the device may be
arranged at a predetermined installation location such as in a tank or, as long as
the cephalopods can extend their arms and eat the feed, the device may be installed
in a movable manner, for example, being suspended from above.
[0022] FIGS. 1A to 1G illustrate seven types of feeders 11 to 17. Hereinafter, the feeder
11 illustrated in FIG. 1A will be described as an example, and then the feeders 12
to 17 as modified examples will be described. The feeder 11 includes an outer shell
1 having a concave portion 1a and a feed 2 placed in the concave portion. The material
of the outer shell 1 may be any material as long as it does not inhibit feeding of
the cephalopods. The material for the outer shell 1 may be an artificial material
such as metal, chinaware, ceramic, synthetic resin, wood, rubber, paper, leather,
glass, or tile, or a natural material such as stone, shell, or bone. In a case where
the outer shell 1 has enough strength to withstand the pressure from the arms of the
cephalopods, the outer shell 1 does not collapse, dissipation of the feed placed in
the concave portion is reduced, and deterioration of the water quality can be prevented,
whereby an appropriate raising environment can be maintained.
[0023] The outer shell 1 of the feeder 11 has a cup shape having a concave portion 1a at
the center. However, the outer shell 1 of the feeder 11 may have any shape as long
as it can feed cephalopods. The shape may be a substantially spherical shape, a substantially
columnar shape, a substantially conical shape, a substantially polyhedral shape, or
a shape resembling a creature eaten by a cephalopod. Examples of organisms that are
eaten by cephalopods include small fish, crustaceans, shellfish, hermit crabs and
squid. The shape of the outer shell 1 of the feeder 11 may be a shape that can be
held by arms of cephalopods. If the outer shell 1 of the feeder 11 has a shape that
can be held by their arms of the cephalopods, more feed can be given to cephalopods
that have a habit of drawing feed near their mouth for eating.
[0024] The size of the outer shell 1 of the feeder 11 is not particularly limited as long
as cephalopods can extend their arms and eat the feed, but for example, when the cephalopods
have a total length of 30 cm, the outer diameter may be approximately from 1 cm to
7 cm. By setting the size of the outer shell 1 of the feeder 11 to the above-described
range, it becomes easier for cephalopods to hold the feed using their arms, so that
eating by the cephalopods can be promoted.
[0025] The concave portion 1a of the outer shell 1 of the feeder 11 may have any shape as
long as the feed can be placed inside the concave portion 1a. The concave portion
1a of the outer shell 1 of the feeder 11 may have a substantially hemispherical shape,
a substantially groove shape, a substantially conical shape, or a substantially tubular
shape penetrating the outer shell 1. In addition, a concave portion provided in natural
materials, such as a stone, a shell, or a bone, may also be used as an outer shell
of the feeder 11 as it is. The concave portion 1a of the outer shell 1 may be formed
so as to cover at least half of the volume of the feed, or to wrap a portion of the
feed so as to be fixed on the outer shell, thereby holding the feed in place inside
the concave portion 1a.
[0026] The feed 2 is placed inside the outer edge of the concave portion 3, that is, inside
the concave portion 1a of the outer shell 1. The feed 2 may be placed in any manner
as long as it is held inside the concave portion 1a. A part of the feed 2 may be directly
bonded to the outer shell 1, or even if it is not bonded to the outer shell 1, it
may be placed so that it is held by being physically covered by the concave portion
of the outer shell 1. When a part of the feed 2 is attached to the outer shell, the
feed 2 is easily held by the outer shell 1 even if there is a water flow caused by,
for example, the movement of the cephalopods, or by the movement of bubbles. An adherent
feed can be produced by using a substance that adheres to the outer shell as a part
of the feed 2. An adherent feed according to the present embodiment is a feed that
can adhere to the concave portion of the outer shell 1 and maintain its shape. The
adherent feed may have, for example, a viscosity of 10 Pa to 100 Pa. Also, the adherent
feed may be a feed having physical properties that maintain its original shape when
exposed to a water flow at a flow rate of 0.1, 1, 5, 10, or 15 cm/s. Also, the adherent
feed may be a feed that easily breaks up in water. Breaking up may be determined by
fragmentation such that the shape of the feed cannot be recognized. A feed that easily
breaks up refers to, for example, a feed that breaks up in about 15 minutes when left
standing in water and breaks up immediately when the cephalopods grab the feed. Examples
of the substance for adhering to the outer shell 1 include proteins such as collagen,
polysaccharides such as fucoidan and carrageenan, phospholipids such as egg membrane,
glycoproteins, and glycolipids. Feed containing protein can promote the growth of
cephalopods.
[0027] The surface shape of the outer shell 1 may be adjusted so that the feed 2 easily
adheres to the outer shell 1 (particularly, inside the concave portion). Examples
of the surface shaping include providing fine irregularities, and providing a plurality
of fine grooves on the surface of the outer shell 1 (the surface inside the concave
portion). The size of the irregularities provided on the surface of the outer shell
1 may be adjusted according to the characteristics of the feed 2.
[0028] The surface shape of the outer shell 1 to which the feed 2 does not adhere may be
adjusted so that the cephalopods can easily hold it using their arms. Examples of
the modification of the surface shaping include providing fine irregularities, and
providing a plurality of fine grooves on the surface of the outer shell 1 (the surface
inside the concave portion). The size of the irregularities provided on the surface
of the outer shell 1 may be changed according to the type and characteristics of the
cephalopods.
[0029] The feed 2 may be any feed as long as it can be eaten by cephalopods. The feed may
be made using one or more feed ingredients. Examples of the feed ingredients include
fish such as horse mackerel, mackerel and sardine, clams such as short-neck clam,
freshwater clam and turban shell, crustaceans such as shrimp, crab and krill, and
grains such as soybean, corn, rice and wheat.
[0030] The feed 2 may be a blended feed. The blended feed may include, for example, ground
fish, shellfish, crustaceans, and cereals. In a case where a blended feed is used
as a feed, it is easy to add a component that promotes the growth of cephalopods,
and to cope flexibly with price fluctuations of feed ingredients. Examples of components
that promote the growth of cephalopods include vitamins, minerals, hormones, prophylactics,
therapeutics, sedatives and vaccines.
[0031] In a case where feeding cephalopods is performed using the feeder 11, the feeder
11 is placed at a position where the cephalopods can eat using their arms, with the
feed 2 attached to the inside of the concave portion provided in the outer shell 1.
When the cephalopods are interested in the feed, they extend their arms and eat the
feed 2. Eating by the cephalopods is promoted by setting the feeder 11, to which the
feed 2 is attached, accessible to the cephalopods. As described above, according to
the feeder and the feeding method according to the present aspect, more feed can be
continuously supplied to the cephalopods. In addition, the feeder and the feeding
method according to the present embodiment promote feeding of cephalopods, such that
residue of the feed in the raising environment and deterioration of the raising environment
can be prevented. In addition, eating by the cephalopods reared by the above-described
feeding method is promoted due to the improved raising environment, so that the nutritional
status of the cephalopods is improved. As a result, damage to the arms or the surface
of the body of the cephalopods is reduced, and the flesh quality of the cephalopods
can be improved so that the taste and umami when served for food are enhanced. In
addition, reduced arm or body surface damage can reduce the risk of infection.
[0032] The timing of feeding the cephalopods may be any time as long as the developed cephalopods
can eat a protein-containing feed. By feeding using a feeder described in the present
aspect, feed intake can be enhanced through eating with arms holding the feed. High
feed intake can be maintained by setting the ratio of feeding using the feeder described
in the present embodiment to 10% or higher, 20% or higher, 30% or higher, or 50% or
higher of the quantity of feed for the cephalopods. Cephalopods that maintain high
growth and have good flesh quality can be developed by feeding them using a feeder
described in the present aspect for one month or more, two months or more, or three
months or more. In addition, by performing feeding using a feeder described in the
present aspect, it is possible for the cephalopods to learn that what is inside the
feeder is food, and quickly eat it.
[0033] The timing of feeding cephalopods may be any time as long as the cephalopods can
eat. When feeding is performed in a 24-hour cycle, the internal clock and the digestion
and absorption cycle in the cephalopods are linked, whereby stress is reduced and
growth is promoted. When giving a light-dark cycle during raising cephalopods, by
linking the light-dark cycle with the feeding timing, the internal clock of the cephalopods
synchronized with the light-dark cycle and the digestive absorption cycle are linked,
whereby stress is reduced and growth is promoted. Feeding cephalopods may be performed
by planned feeding giving a predetermined amount, or by satiation in which feed consumption
is observed while feeding, and feeding is maintained as long as eating continues.
[0034] The cephalopods raised by the feeder of the present invention can be used not only
for human food applications including raw foods, processed foods, frozen foods, chilled
foods, and dried foods, but also as raw material for food, feed applications, ornamental
applications, and as raw material for extracting useful components. The cephalopods
raised by a feeder of the present invention are excellent in growth and rich in proteins,
so they have good taste, contain many components that contribute to health, and are
excellent for food applications.
[0035] Feeders 12 to 17 according to variations will be described with reference to FIGS.
1A to 1G. The feeder 12 illustrated in FIG. 1B is an example in which the outer shell
1 has a substantially square pillar shape. In addition, the outer edge of the concave
portion 3 is rectangular in plan view, and the concave portion 1a of the outer shell
1 is also substantially square pillar-shaped. The outer shape of the feeder 13 illustrated
in FIG. 1C formed of an outer shell 1 and a feed 2 is substantially a square pillar
shape, like the feeder 12, but can be regarded as having the side wall is partially
removed as compared with the feeder 12. The outer shell 1 of the feeder 13 has a square
pillar shape part (one side) of which is open, the inner side thereof being a concave
portion 1a, and a feed 2 is placed therein. As a result, the feed 2 is exposed at
the opening 2a and at the openings 2b and 2c at both ends of the square pillar outer
shell 1 (the opening 2c is an end opposite to the opening 2b). For this reason, cephalopods
can easily eat the feed using the openings 2a to 2c.
[0036] The feeder 14 illustrated in FIG. 1D has a cup shape having a concave portion 1a
at the center similarly to the feeder 11, but its depth is smaller than that of the
feeder 11. Therefore a large exposed surface of the feed 2 is secured, so that cephalopods
can easily eat the feed 2. The feeder 15 illustrated in FIG. 1E has a semicircular
arc shape in cross section, and the feed 2 is attached to the inside of the arc portion
of an outer shell 1 extending in the depth direction in the figure. That is, the inside
of the arc portion functions as a concave portion 1a. In the case of a feeder 15 having
such a shape, the exposed surface of the feed 2 becomes large, similarly to the feeder
13, so that cephalopods can easily ingest the feed 2.
[0037] In the feeder 16 illustrated in FIG. 1F, an outer shell 1 has a substantially ball
shape, and a plurality of groove-shaped concave portions 1a extending in the circumferential
direction are formed around the outer shell 1, and a feed 2 is attached to the inside.
A concave portion outer edge 3 is formed between two adjacent grooves. Like the feeder
16, a plurality of concave portions 1a for accommodating the feed 2 may be provided
in one outer shell 1. Even in the case of such a configuration, the exposed surface
of the feed 2 is large, so that cephalopods can easily eat the feed 2. In the feeder
17 illustrated in FIG. 1G, a plurality of through-holes 1b (six in FIG. 1G) are provided
in a columnar outer shell 1, and a feed 2 is filled in each through-hole 1b. That
is, the through-hole 1b functions as a concave portion for accommodating the feed
2. Also in the feeder 17, similarly to the feeder 16, a plurality of concave portions
for accommodating the feed 2 are provided in one outer shell 1. In order to hold the
feed 2, the through-hole 1b does not have to penetrate. In this manner, the shape
of the feeder may be appropriately changed. Further, the shapes of the outer shell
and the concave portion may be appropriately changed. Note that a feeder combining
features of different feeders among the feeders 11 to 17 may be used.
EXAMPLES
[0038] Embodiments of the present invention are described below in detail using examples.
However, the present invention is not limited in any manner by these examples. Unless
specified otherwise, "%" is indicated on a mass basis.
(1) RAISING OF COMMON OCTOPUS
Example 1
[0039] A synthetic resin pipe having a length of 5 cm and an outer diameter of 20 mm was
prepared as an outer shell. Minced fish meat was filled as a feed into a concave portion
of the pipe having an inner diameter of 18 mm, thus producing a feeder according to
Example 1. In this feeder the outer shell 1 is cylindrical, and a cylindrical region
inside the pipe is the concave portion for accommodating the feed.
[0040] A feeder according to Example 1 was used for five common octopuses of about 200 g
in a land tank; the common octopuses immediately held the feeder with their arms and
started eating the feed. Thirty minutes later, the feed placed in the concave portion
of the synthetic resin pipe was completely consumed. In addition, the type of feed
was changed, and a feed prepared by mixing minced fish meat and minced shellfish meat,
and a feed prepared by mixing minced fish meat with 20% gelatin, were fed to the common
octopuses in the same manner. In each case the common octopuses immediately held the
pipe as a feeder with their arms and started eating the feeds, and after 30 minutes,
had completely eaten the feed placed in the concave portion of the synthetic resin
pipe.
Comparative Example 1
[0041] For Comparative Example 1, a feed containing 20% gelatin mixed with minced fish meat
was directly fed to the common octopuses without being placed in the outer shell.
As a result, the common octopuses held the feed with their arms, but stopped eating
the feeds part-way through, and about 50% or more of the feed remained in the tank.
In addition, the remaining feeds broke up in the water, so that the water quality
deteriorated and the broken feeds were not eaten.
[0042] The type of feed was changed; a feed containing from 1 to 5% salt in minced fish
meat and a feed containing 5% starch in minced fish meat were prepared, and fed to
the common octopus as they were without being placed in the outer shell. As a result,
in each case, the common octopuses held the feeds with their arms, but stopped eating
the feeds part-way through, and about 50% or more of the feeds remained in the tank.
The remaining feeds broke up in the water, so that the water quality deteriorated
and the broken feeds were not eaten. In addition, the breaking up of the feed was
also observed during feed eating by the common octopuses, and the water quality deteriorated
even in the rare case where the feeds were completely eaten. When these feeds were
given for three days or more, in some cases no feed was eaten, and stagnation of growth
was observed.
[0043] In Example 1 minced fish meat alone was used as feed, but the minced fish meat was
weakly formed and could not be fed directly to the common octopuses.
(2) EVALUATION OF RAISING PERFORMANCE
[0044] The common octopuses cultured with the feeds used in Example 1 showed a strong appetite
continuously for three months or more. As for the raising results, the survival rate
was 100%, and the body weight of each octopus increased five times or more. All of
the octopuses had less damage to their arms and body surface, and when provided for
human consumption, had a rich taste and a strong umami. In the common octopuses cultured
with the feeds used in Comparative Example 1, damage to their arms and body surface
was observed.
[0045] As described above, according to the present invention, feed intake by cephalopods
can be improved. Further, according to the present invention, deterioration of a raising
environment for cephalopods can be prevented. Further, according to the present invention,
it is possible to obtain cephalopods having a good taste and a large amount of components
contributing to health.
Reference Signs List
[0046]
- 1
- Outer shell
- 1a
- Concave portion
- 1b
- Through-hole
- 2
- Feed
- 3
- Outer edge of concave portion
- 11 - 17
- Feeders